Exports during multi-RDSR import can cause errors

[Ed McDonagh]

Refs #114

Some processes aren't being caught by the DoesNotExist try except

[Ed McDonagh]

Refs #614 - will need to implement on live server and try to trigger...

→ <<cset 4652fd4e552f>>

[Ed McDonagh]

Added ref #614 to changes.

→ <<cset 9dcd250fbe03>>

[Ed McDonagh]

Merged in issue614multiRDSRexports (pull request #178)

Added try except for multi-RDSR during sheet creation

Fixes #614

→ <<cset a24b8c6948cf>>